1. Field of the Invention
The present invention relates to a gas-quenching cell, and more specifically, to the gas stirring system for such a cell.
2. Discussion of the Related Art
Gas-quenching methods have many advantages as compared to liquid-quenching methods, especially the fact that the processed elements remain dry and clean.
The paper entitled "La vitesse de refroidissement, point capital pour le traitement en fours sous vide" by J. Naudot, published in "Traitement thermique" N.degree.133-79, France, discusses the influence of several parameters and of the gas choice on the efficiency of the quenching, mainly on the quenching speed. It is constant that if the quenching speed is to be increased, the gas mass flow, that is, its speed and its static pressure should be increased. The above-mentioned paper mentions that beyond 4 to 5 bars of static nitrogen pressure, the efficiency gain is to be tempered by the cost of the high power engines necessary for the stirring and the high gas consumption.
European patent 0,313,888 discloses using light gases, such as helium or hydrogen, at high static pressures. The power of the stirring engines would then be comparable to that reached for heavier gases at lower pressures. However, light gases are particularly expensive (helium) or dangerous (hydrogen).
The quenching efficiency, such as defined in the above documents, is relative to the quenching speed.
Gas-quenching installations are presently used only for quenching operations, since they are generally optimized to obtain as high a gas mass flow as possible.